排序方式: 共有53条查询结果,搜索用时 296 毫秒
1.
McIntosh R Ellis D Gil-Lostes J Dalby KJ Rosair GM Welch AJ 《Dalton transactions (Cambridge, England : 2003)》2005,(10):1842-1846
Reduction of the tethered carborane 1,2-(CH2)3-1,2-closo-C2B10H10 followed by treatment with CoCl2/NaCp, [(p-cymene)RuCl2]2(p-cymene=C6H4MeiPr-1,4), (PMe2Ph)2PtCl2 or (dppe)NiCl2(dppe=Ph2PCH2CH2PPh2) affords reasonable yields of the new 13-vertex metallacarboranes 1,2-(CH2)3-4-Cp-4,1,2-closo-CoC2B10H10 (1), 1,2-(CH2)3-4-(p-cymene)-4,1,2-closo-RuC2B10H10 (2), 1,2-(CH2)3-4,4-(PMe2Ph)2-4,1,2-closo-PtC2B10H10 (3) and 1,2-(CH2)3-4,4-(dppe)-4,1,2-closo-NiC2B10H10 (4), respectively. All compounds were characterised spectroscopically and crystallographically. The cobalt and ruthenium species 1 and 2 have Cs symmetry in both solution and the solid state, having henicosahedral cage structures featuring a trapezoidal C1C2B9B5 face. The platinum and nickel compounds 3 and 4 have asymmetric docosahedral cage structures in the crystal (the more so for 4 than for 3) although both appear, by 11B and 31P NMR spectroscopy, to have Cs symmetry in solution. Low-temperature experiments on the more soluble platinacarborane could not freeze out the diamond-trapezium-diamond fluctional process that we assume is operating in solution, and we therefore conclude that this process has a relatively low activation barrier, probably <35 kJ mol-1. 相似文献
2.
N. Andersen T. Andersen P. Dalby T. Royer 《Zeitschrift für Physik D Atoms, Molecules and Clusters》1988,9(4):315-318
The orientation of Na(3p) states created in 3–13 keV Na(3s)-He collisions has been studied by the polarised photon-scattered particle coincidence technique at scattering angles corresponding to the impact-parameter range 1–2 a.u. In the standard geometry, at large impact parameters the excitation process exhibits a very high degree of orientation with about 90% of the Na(3p) states havingm 1=?1. Strong reduction in this propensity is observed at impact parameters smaller than about 1.3 a.u., where a molecular curve crossing causes simultaneous He(n=2) excitation. In this region, also ionisation becomes important. 相似文献
3.
4.
Prof. Dr. Ian Paterson Mengyang Xuan Dr. Stephen M. Dalby 《Angewandte Chemie (International ed. in English)》2014,53(28):7286-7289
As a potent neurotrophic agent, the sesquiterpenoid jiadifenolide represents a valuable small‐molecule lead for the potential therapeutic treatment of neurodegenerative diseases. A stereocontrolled total synthesis of this densely functionalized natural product is reported, central to which is an adventurous samarium‐mediated cyclization reaction to establish the tricyclic core and the adjacent C5 and C6 quaternary stereocenters. 相似文献
5.
[reaction: see text] A stereo-controlled synthesis of the fully elaborated C26-C40 tricyclic [5,6,6]-bis-spiroacetal of spirastrellolide A containing the C28 chlorine substituent is reported, exploiting asymmetric Sharpless dihydroxylation and boron-mediated allylation methodology. 相似文献
6.
7.
Bing-Xin Yang Yi-Han Kao Janos Kirz Chang-Xin Gu R.N. Bhargava D.A. Cammack R.J. Dalby 《Physics letters. A》1985,113(5):283-288
Transmission measurements of the extended X-ray absorption fine structure above the oxygen K-edge have been made by using a new scintillation detection technique. The absorption spectrum is in close resemblance with the total electron yield spectrum recorded at the same time. This new technique is of interest for studies of soft X-ray absorption spectroscopy for thin films of solid materials. 相似文献
8.
9.
10.